利用 BackGroundWorker 跨线程调用 Winforms 控件上的 GUI 操作?

问题描述

灵感来自我自己使用多线程 Winforms 应用程序的经验，以及诸如

Inspired by my own experience with multithreaded Winforms applications, as well as questions such as

• 避免调用的麻烦/BeginInvoke 在跨线程 WinForm 事件处理中?
• 避免在释放控件时调用 Invoke

我想出了一个非常简单的模式，我想验证它的可靠性.

I've come up with a very simple pattern, whose soundness I would like to verify.

基本上，我正在创建(并在应用程序的整个生命周期中运行)一个 BGW，其唯一目的是同步调用请求.考虑:

Basically I'm creating (and running throughout the application's lifetime) a BGW whose sole purpose is the synchronization of invoke requests. Consider:

public MainForm()
{
    InitializeComponent();
    InitInvocationSyncWorker();
}

private void InitInvocationSyncWorker()
{
    InvocationSync_Worker.RunWorkerAsync();
}

private void InvocationSync_Worker_DoWork(object sender, DoWorkEventArgs e)
{
    Thread.Sleep(Timeout.Infinite);
}

void InvokeViaSyncWorker(Action guiAction)
{
    InvocationSync_Worker.ReportProgress(0, guiAction);
}

private void InvocationSync_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
    if (IsDisposed) return; //we're in the GUI thread now, so no race condition right?

    var action = (Action) e.UserState;
    action();
}

public void SomeMethodCalledFromAnyThread() //Sample usage
{
    InvokeViaSyncWorker(() => MyTextBox.Text = "Hello from another thread!"));
}

当然，这不是最经济的方法(像这样保持线程活跃)，但如果它有效并且我没有错过任何东西，那肯定是我见过的最简单的方法.

Granted, it's not the most economical of approaches (keeping a thread alive like that), but if it works and I haven't missed anything, it sure is the simplest I've seen.

非常感谢您的反馈！

推荐答案

没有必要为此开一个线程.只需使用 SynchronizationContext，如下所示:

There's no need to open a thread just for that. Simply use SynchronizationContext, like so:

private readonly SynchronizationContext _syncContext;

public MainForm()
{
    InitializeComponent();

    _syncContext = SynchronizationContext.Current;
}

void InvokeViaSyncContext(Action uiAction)
{
    _syncContext.Post(o =>
    {
        if (IsHandleCreated && !IsDisposed) uiAction();
    }, null);
}

public void SomeMethodCalledFromAnyThread() //Sample usage
{
    InvokeViaSyncContext(() => MyTextBox.Text = "Hello from another thread!"));
}

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